1. Field of the Invention
The present invention relates to a data processing method and apparatus for calculating a killer ratio resulting from a specified defect, and an information storage medium for storing programs as software which cause a computer to execute various processing operations.
2. Description of the Related Art
Currently, IC (Integrated Circuit) chips are generally mass-produced by dividing a single semiconductor wafer into a plurality of dies and then manufacturing integrated circuits of the same structure on the respective dies. Various approaches for improving the yields of such mass-produced IC chips are also studied, and for example, the calculation of a killer ratio is performed based on past die research data and yield data.
The killer ratio refers to an expected value of the probability that, when a defect of one type is specified, the specified defect present on a die results in a defective IC chip manufactured from the die. For example, when one die and a defect of one type are specified, the specified defect present on the specified die does not necessarily cause the specified die to be defective. Also, even when the specified defect is not present on the specified die, the specified die may become defective due to another type of defect.
The die research data includes, for example, defect presence/absence data for indicating the presence or absence of defects for each type and result pass/fail data for indicating whether a manufacturing result is favorable or unfavorable, for each die identification data which identifies a plurality of dies. The die research data is registered for each of a plurality of manufacturing steps which are performed on a single wafer.
The aforementioned defect presence/absence data is collected from a plurality of dies for each of a plurality of manufacturing steps when a semiconductor wafer is divided into a plurality of dies to mass-produce a plurality of IC chips through various manufacturing steps, while the result pass/fail data is collected by performing a final test of each of a plurality of finished IC chips.
It should be noted that while a plurality of sets of die research data in a single manufacturing step of a single semiconductor wafer are herein referred as an example as mentioned above for simplifying description, a number of sets of die research data for a plurality of manufacturing steps of a single semiconductor wafer are generally collected and accumulated corresponding to a plurality of semiconductor wafers of a lot, and a number of sets of die research data for each lot is collected and accumulated corresponding to a plurality of lots.
As shown in FIG. 1(a), when a defect of one type is specified, die research data of a plurality of dies from a single semiconductor wafer is classified into four: xe2x80x9cspecified defect present and manufacturing result favorablexe2x80x9d; xe2x80x9cspecified defect present and manufacturing result unfavorablexe2x80x9d; xe2x80x9cspecified defect absent and manufacturing result favorablexe2x80x9d; and xe2x80x9cspecified defect absent and manufacturing result unfavorablexe2x80x9d, as shown in FIG. 1(b).
In this case, assuming that the total number of dies with the specified defect present thereon is Txe2x80x2, and the number of dies with the specified defect present thereon and a favorable manufacturing result is TGxe2x80x2, then a killer ratio KR is given by:
KR=(the number of dies with the specified defect and an unfavorable manufacturing result)/(the total number of dies with the specified defect)=1xe2x88x92(the number of dies with the specified defect and a favorable manufacturing result)/(the total number of dies with the specified defect)=1xe2x88x92TGxe2x80x2/Txe2x80x2xe2x80x83xe2x80x83(1)
The calculation of the killer ratio with one of a plurality of types of defects being specified as mentioned above can predict the ratio at which a finished IC chip manufactured from a die becomes defective when the specified defect is present on the die. However, the aforementioned calculation method of the killer ratio does not consider a defective IC chip due to unspecified defects, resulting in unsatisfactory calculation accuracy of the killer ratio.
Thus, a calculation method has been proposed for improving the accuracy of the killer ratio by considering the effects of unspecified defects. The method assumes that all types of defects are randomly distributed over the entire region of a semiconductor wafer and a die has the specified defect and another kind of defect mixed thereon.
A survival rate (a ratio at which its manufacturing result is favorable) is detected for dies with no specified defect and is used as xe2x80x9ca baseline yieldxe2x80x9d which is a survival rate of unspecified defects. Assuming that the total number of dies is T and the number of dies with a favorable manufacturing result is TG, then the baseline yield Yb is given by:
xe2x80x83Yb=(TGxe2x88x92TGxe2x80x2)/(Txe2x88x92Txe2x80x2)xe2x80x83xe2x80x83(2)
When the aforementioned equation (1) is corrected by the above equation (2), the effects of types of defects other can be eliminated from the killer ratio of dies with the specified defect. The killer ratio KRM in this case is given by:
KRM=1xe2x88x92(TGxe2x88x92Txe2x80x2)/Yb=1xe2x88x92[TGxe2x80x2(Txe2x88x92Txe2x80x2)]/[Txe2x80x2(TGxe2x88x92TGxe2x80x2)]xe2x80x83xe2x80x83(3)
The aforementioned calculation method of the killer ratio resulting from a specified defect has satisfactory accuracy since it can eliminate the effects of unspecified other kinds of defects. However, even with the aforementioned calculation method of the killer ratio, the number of the specified defects present on a single die is not taken into account, thereby reducing the accuracy of the killer ratio calculation due to differences in the number.
The present invention has been made in view of the aforementioned problems, and it is an object thereof to provide a data processing method and apparatus capable of calculating a killer ratio with more satisfactory accuracy than that in the prior art, and an information storage medium for storing programs as software which cause a computer to execute processing operations of the data processing method of the present invention.
According to a first aspect of the present invention, the data processing apparatus comprises data storing means for previously registering die research data which includes at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, data input means for receiving type selecting data for selecting a specified defect which is a defect of one type, data retrieving means for retrieving the die research data corresponding to the specified defect from the data storing means with the type selecting data input to the data input means, data classifying means for classifying the die research data retrieved by the data retrieving means based on the number of the specified defects present on a die, and first calculating means for calculating a killer ratio for each of a plurality of groups of die research data classified by the data classifying means.
Therefore, in the data processing method with the data processing apparatus of the present invention, the die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer is previously registered in the data storing means. In such a state, when the type selecting data for selecting a specified defect which is a defect of one type is input to the data input means, the data retrieving means retrieves the die research data corresponding to the specified defect from the data storing means with the input type selecting data. The data classifying means classifies the retrieved die research data based on the number of the specified defects present on a die, and the first calculating means calculates the killer ratio for each of a plurality of groups of the classified die research data. The killer ratios for the plurality of groups thus calculated are provided for the respective groups classified based on the number of the specified defects present on a die.
The data processing apparatus as described above may comprise second calculating means for calculating a killer ratio in the case of one specified defect for each of the groups from the killer ratio for each of the groups calculated by the first calculating means. In this case, since the second calculating means calculates a killer ratio in the case of one specified defect for each of the groups from the killer ratio for each of the groups calculated by the first calculating means, a killer ratio when a plurality of specified defects present on a die are assumed to be one is calculated.
The data processing apparatus as described above may comprise third calculating means for calculating one killer ratio as the average value of the killer ratios for the groups calculated by the second calculating means. In this case, since the third calculating means calculates one killer ratio as the average value of the killer ratios for the groups calculated by the second calculating means, one killer ratio which reflects the effect of the number of the specified defects present on a die is calculated.
In the data processing apparatus as described above, the third calculating means may weight the killer ratio for each of the groups in accordance with the number of the specified defects when it calculates the one killer ratio as the average value. In this case, since the third calculating means calculates one killer ratio by weighting the killer ratio for each of the groups in accordance with the number of the specified defects, the effect of the number of the specified defects present on a die is appropriately reflected in the calculation result of the killer ratio.
In the data processing apparatus as described above, the third calculating means may assign a heavier weight to a killer ratio in a group with a larger number of the specified defects. In this case, since the third calculating means assigns a heavier weight to a killer ratio in a group with a larger number of the specified defects, the effect of the number of the specified defects present on a die is more appropriately reflected in the calculation result of the killer ratio.
In the data processing apparatus as described above, the third calculating means may weight the killer ratio in accordance with the ratio of the total number of the specified defects present on a single wafer to the total number of the specified defects for each of the groups. In this case, the third calculating means weights the killer ratio in accordance with the ratio of the total number of the specified defects present on a single wafer to the total number of the specified defects for each of the groups, the effect of the number of the specified defects present on a die is more appropriately reflected in the calculation result of the killer ratio.
The data processing apparatus as described above may comprise data extracting means for extracting dies with no specified defect from the die research data retrieved by the data retrieving means, correction generating means for generating corrected data which reflects the effects of types of defects other than the specified defect from the die research data extracted by the data extracting means, and result correcting means for correcting the killer ratio with the corrected data generated by the correction generating means.
In this case, the data extracting means extracts die with no specified defect from the die research data retrieved by the data retrieving means, and the correction generating means generates corrected data which reflects the effects of types of defects other than the specified defect from the extracted die research data. The result correcting means corrects the killer ratio with the generated corrected data, thereby eliminating the effects of kinds of defects other than the specified defect from the killer ratio which reflects the effect of the number of the specified defects present on a die.
According to a second aspect of the present invention, the data processing apparatus comprises data storing means for previously registering die research data which includes at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, data input means for receiving type selecting data for selecting a specified defect which is a defect of one type, data retrieving means for retrieving the die research data corresponding to the specified defect from the data storing means with the type selecting data input to the data input means, data classifying means for classifying the die research data retrieved by the data retrieving means based on the number of the specified defects present on a die, and killer ratio calculating means for detecting, from a plurality of groups of the die research data classified by the data classifying means, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer, and calculating a killer ratio KRxe2x80x2 resulting from the specified defect as follows;
KRxe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[TGi/Ti]1/i}
Therefore, in the data processing method with the data processing apparatus of the present invention, the die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer is previously registered in the data storing means. In such a state, when the type selecting data for selecting a specified defect which is a defect of one type is input to the data input means, the data retrieving means retrieves the die research data corresponding to the specified defect from the data storing means with the input type selecting data. The killer ratio calculating means detects, from the retrieved die research data, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer, and calculates a killer ratio KRxe2x80x2 resulting from the specified defect as KRxe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[TGi/Ti]1/i}. Thus, one killer ratio which reflects the effect of the number of the specified defects present on a die is calculated.
According to a third aspect of the present invention, the data processing apparatus comprises data storing means for previously registering die research data which includes at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, data input means for receiving type selecting data for selecting a specified defect which is a defect of one type, data retrieving means for retrieving the die research data corresponding to the specified defect from the data storing means with the type selecting data input to the data input means, data classifying means for classifying the die research data retrieved by the data retrieving means based on the number of the specified defects present on a die, and killer ratio calculating means for detecting, from a plurality of groups of the die research data classified by the data classifying means, the total number of dies T present in the wafer, the number of dies Txe2x80x2 with the specified defect, the number of dies TG with a favorable manufacturing result, the number of dies TGxe2x80x2 with the specified defect and a favorable manufacturing result, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer, and calculating a killer ratio KR1xe2x80x2 resulting from the specified defect as follows:
KR1xe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[(TGi(Txe2x88x92Txe2x80x2))/(Ti(TGxe2x88x92TGxe2x80x2))]1/i}
Therefore, in the data processing method with the data processing apparatus of the present invention, the die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer is previously registered in the data storing means. In such a state, when the type selecting data for selecting a specified defect which is a defect of one type is input to the data input means, the data retrieving means retrieves the die research data corresponding to the specified defect from the data storing means with the input type selecting data. The killer ratio calculating means detects, from the retrieved die research data, the total number of dies T present in the wafer, the number of dies Txe2x80x2 with the specified defect, the number of dies TG with a favorable manufacturing result, the number of dies TGxe2x80x2 with the specified defect and a favorable manufacturing result, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer, and calculates a killer ratio KR1xe2x80x2 resulting from the specified defect as KR1xe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[(TGi(Txe2x88x92Txe2x80x2))/(Ti(TGxe2x88x92TGxe2x80x2))]1/i}. Thus, one killer ratio which reflects the effect of the number of the specified defects present on a die is calculated with the effects of kinds of defects other than the specified defect being eliminated.
It should be noted that various means in the present invention may be any which is formed to realize their functions, and allow dedicated hardware for generating a predetermined function, a computer provided with a predetermined function by means of programs, a predetermined function realized in the computer with programs, a combination thereof, or the like.
For example, the data storing means may be any which stores various registered data, and allows a storage area of an information storage means such as RAM (Random Access Memory), for example. The data input means may be any which receives various data input thereto, and allows a keyboard which receives data input through manual operations, a communication I/F (Interface) which receives data input through signal reception, and a drive device which retrieves recorded data from an information storage medium such as FD (Floppy Disc), CD (Compact Disc)-ROM (Read Only Memory) or the like.
According to a first aspect of the present invention, the information storage medium stores software readable by a computer as programs which causes the computer to execute: storing die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer; receiving type selecting data for selecting a specified defect which is a defect of one type; retrieving the die research data corresponding to the specified defect with the input type selecting data; classifying the retrieved die research data based on the number of the specified defects present on a die; calculating a killer ratio for each of a plurality of groups of the classified die research data; calculating a killer ratio in the case of one specified defect for each of the groups from the calculated killer ratio for each of the groups; weighting the calculated killer ratio for each of the groups in accordance with the number of the specified defects; and calculating one killer ratio as the average value of the weighted killer ratios for the groups.
Therefore, when a computer reads the programs stored in the information storage medium of the present invention to perform corresponding processing operations, the computer stores die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, and, in this state, receives input type selecting data for selecting a specified defect which is a defect of one type. The die research data corresponding to the specified defect is retrieved with the input type selecting data, and the retrieved die research data is classified based on the number of the specified defects present on a die. A killer ratio is calculated for each of a plurality of groups of the classified die research data, and a killer ratio in the case of one specified defect is calculated for each of the groups from the calculated killer ratio for each of the groups. The calculated killer ratio for each of the groups is weighted in accordance with the number of the specified defects, and one killer ratio is calculated as the average value of the weighted killer ratios for the groups, thereby calculating one killer ratio which reflects the effect of the number of the specified defects present on a die.
According to a second aspect of the present invention, the information storage medium stores software readable by a computer as programs which causes the computer to execute: storing die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer; receiving type selecting data for selecting a specified defect which is a defect of one type; retrieving the die research data corresponding to the specified defect with the input type selecting data; classifying the retrieved die research data based on the number of the specified defects present on a die; detecting, from the classified die research data, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer; and calculating a killer ratio KRxe2x80x2 resulting from the specified defect as KRxe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[TGi/Ti]1/i}.
Therefore, when a computer reads the programs stored in the information storage medium of the present invention to perform corresponding processing operations, the computer stores die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, and, in this state, receives input type selecting data for selecting a specified defect which is a defect of one type. The die research data corresponding to the specified defect is retrieved with the input type selecting data, and the retrieved die research data is classified based on the number of the specified defects present on a die. From the classified die research data, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer are detected, and a killer ratio KRxe2x80x2 resulting from the specified defect is calculated as KRxe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[TGi/Ti]1/i}. Thus, one killer ratio which reflects the effect of the number of the specified defects present on a die is calculated.
According to a third aspect of the present invention, the information storage medium stores software readable by a computer as programs which causes the computer to execute: storing die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer; receiving type selecting data for selecting a specified defect which is a defect of one type; retrieving the die research data corresponding to the specified defect with the input type selecting data; classifying the retrieved die research data based on the number of the specified defects present on a die; detecting, from the classified die research data, total number of dies T present in the wafer, the number of dies Txe2x80x2 with the specified defect, the number of dies TG with a favorable manufacturing result, the number of dies TGxe2x80x2 with the specified defect and a favorable manufacturing result, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer; and calculating a killer ratio KR1xe2x80x2 resulting from the specified defect as KR1xe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[(TGi(Txe2x88x92Txe2x80x2))/(Ti(TGxe2x88x92TGxe2x80x2))]1/i}.
Therefore, when a computer reads the programs stored in the information storage medium of the present invention to perform corresponding processing operations, the computer stores die research data including at least the number of defects for each type and manufacturing result pass/fail for each of a plurality of dies divided from a single wafer, and, in this state, receives input type selecting data for selecting a specified defect which is a defect of one type. The die research data corresponding to the specified defect is retrieved with the input type selecting data, and the retrieved die research data is classified based on the number of the specified defects present on a die. From the classified die research data, the total number of dies T present in the wafer, the number of dies Txe2x80x2 with the specified defect, the number of dies TG with a favorable manufacturing result, the number of dies TGxe2x80x2 with the specified defect and a favorable manufacturing result, the number of dies Ti with i specified defects, the number of dies TGi with i specified defects and a favorable manufacturing result, and the total number of specified defects Nxe2x80x2 present in the wafer are detected, and a killer ratio KR1xe2x80x2 resulting from the specified defect is calculated as KR1xe2x80x2=xcexa3(Tixc2x7i/Nxe2x80x2){1xe2x88x92[(TGi(Txe2x88x92Txe2x80x2))/(Ti(TGxe2x88x92TGxe2x80x2))]1/i}. Thus, one killer ratio which reflects the effect of the number of the specified defects present on a die is calculated with the effects of kinds of defects other than the specified defect being eliminated.
It should be noted that the information storage medium in the present invention may be any which previously stores programs for causing the computer to execute various processing as software, and for example, an ROM or HDD (Hard Disc Drive) fixed in an apparatus having a computer as a part thereof, and CD (Compact Disc)-ROM (Read Only Memory) or FD which is removably loaded in an apparatus having a computer as a part thereof are allowed.
The computer in the present invention may be any which can read programs comprising software to execute corresponding processing operations, and for example, an apparatus having a CPU (Central Processing Unit) as a main portion to which various devices such as ROMs, RAMs or I/Fs are connected as required is allowed.
The execution of various operations by the computer corresponding to software in the present invention contemplates that the computer controls the operations of various devices. For example, the data storage by the computer contemplates that the computer stores various data in an information storage medium such as RAM previously connected thereto, that the computer stores various data in an internal memory included therein, or that the computer stores various data in an FD when the FD is used as the information storage medium in the present invention.